Oil burner and system



y 2, 1944' c. L. RAYFIELD 2,347,843

OIL BURNER AND SYSTEM Origihal Filed Sept. 27, 1939 4 Sheets-Sheet l May 2, 1944- c. 1.. RAYFIELD OIL BURNER AND SYSTEM 4 Sheets-Sheet 2 Original Filed Sept. 27, 1939 E17 122 (HA/@155 1. PA rF/flb y 1944- c. L. RAYFIELD 3 OIL BURNER AND SYSTEM Original Filed Sept. 27, 1939 4 Sheet-Shet 5 y 2, 1944- c. L. RAYFIELD' 2,347,843

OIL BURNER AND SYSTEM Original Filed Sept. 27, 1939 4 Sheets-Sheet 4 EMEfiLt E (HARLE A RAW/[A0 Patented May 2, 1944 s OIL BURNER SYSTEM Charles L. Rayfield, Chicago, Ill., assignor to O. L. Rayfleld Company, Chicago, 111., a corporation of Illinois Original application September 27, 1939, Serial Divided and this application N vember 10, 1941, Serial No. 418,531

3 Claims.

The present invention is a division of my copending application entitled Oil burner and system filed September 27, 1939, U. S. Serial No. 296,718 and relates in general to improved means for the burning of oil for heating purposes. More particularly, my invention is concerned with improvements in such apparatus to the end that the less expensive, more viscous oils containing a greater number of heat units may be efficiently utilized for heating purposes and to the end that purging and flushing the apparatus when not in use may be accomplished.

Heretofore, oil burners for domestic heating, such as utilized for the heating of homes, apartment buildings, and the like, have been limited almost entirely to the use of the more highly refined and lighter oils which not only contain a less number of heat units, but are more expensive than the heavier and more viscous oils.

This limitation has resulted to a large extent from the apparent inability of manufacturers to heretofore build suitable apparatus for efficiently burning the heavier grades of oil, which could be assembled into a compact unit suitable for domestic installations. Where attempts were made to use the heavier oils, the installed apparatus usually entailed a complicated arrangement of piping between widely spacedparts of the apparatus and required considerable space for installation, all of which was objectionable and unsightly, especially in cases where the spaces containing the burner apparatus were to be utilized for game and play rooms, and the like.

More specifically, most oil burners are arranged to burn the so-called Light oil No. 3, and it has heretofore been diflicult to provide satisfactory apparatus for domestic heating which could be efiiciently utilized to burn oils as heavy as the so-called No. 5 or No. 6.?

Having the foregoing in mind, the present invention contemplates as a primary object the provision of an improved oil burner and system which will efficiently and economically burn the heavier, more viscous oils.

A further object of the invention is to provide improved means in an oil burner and system for purging and flushing the oil nozzle, when the burner. is shut do Another object of the invention is to provide an improved relief arrangement in the oil path of the burner, whereby oil may be returned to a source of supply, whenever the burner nozzle becomes clogged.

A still further object of the herein. described invention is to provide an improved oil burner in which metered quantitites of oil are burned, and any surplus pumped oil is automatically bypassed back to a supply source.

Other objects and features of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings, which illustrate a single embodiment thereof, and in which:

Figure 1 is a plan view of oil burner apparatus embodying the features of the present invention;

Figure 2 is a longitudinal sectional view taken through the pumping part of the apparatus to show the details of the construction thereof, taken substantially on line IIH of Figure 1;

Figure 3 is a detailed view, partly in section, showing the valving arrangement of the pumping parts, taken substantially on line III -III of Figure 2;

Figure 4 is a view looking into the housing-for certain of the control equipment mounted on the burner, the cover of the housing being removed to show the control elements therein;

Figure 5 is an enlarged fragmentary sectional view showing the details of construction of the bleeder valve as utilized in the present invention; taken substantially on line VV of Figure 1;

' Figure 6 is an enlarged fragmentary sectional view of the carburetor construction utilized in the present invention, taken substantially on line VI-VI of Figure 1; and

Figure 7 is a schematic view of the oil burner and diagrammatically disclosing the piping systems for oil and air, and also diagrammatically showing he control equipment and the electrical connections thereof.

As shown on the drawings:

From a consideration of the apparatus illustrated in Figure 1 of the drawings, it will be apparent that the oil burner and system of the present invention provides a compact unit assembly which may be readily applied to already installed or existing furnaces and boilers for heating purposes.

Burner apparatus in general I As shown in Figure 1, the burner unit com-- prises in general an air blower A, fuel pumping mechanism B, and a main driving motor C for actuating the blower and pumping mechanism.

The blower A is of conventional construction and comprises a main housing portion ID for enclosingthe blower blades orimpeller (not shown) which is connected to the driving shaft of the motor. end in a tubular extension II which forms an air inlet to the center of the housing [0, the extension being circumferentially provided with a plurality of spaced air inlet openings I2., Control of the inlet openings I2 isaccomplished by means of a slide plate l3 which is suitably supported on the outer surface of the extension II for sliding movement thereover.

provided with spaced openings H which are adapted'to cooperate with the openings I2 and vary the efl'ectiveair inlet openings so as to vary the amount of inlet air taken in by the blower.

The-housing "is provided with a tubular ex-. tension l5 on its forward side, this extension defining an air'nozzle for supplying themain combustion air to a fuel atomizing nozzle l6 mounted therein, as shown in Figure 7.

Returning again to Figure 1, the. pumping mechanism B comprises a rotary typeof pump I! for the pumping of oil only, and a second pump 18 of the reciprocable type for the pumping of air and oil for a purpose which will hereafter be more fully explained.

The rotary pump His providedgwith a suitable pipe connection fitting [9 at its'inlet, and

a suitable pipe connection fitting 20 at its outlet. I r

The reciprocating pump I8, as more specifically shown in Figure 2., comprises a housing or'casing 2| which serves at one side. as a support for the rotary pump housing structure 22 which encloses the rotary pump rotor 23, this rotor being mounted at one end of ashaftz l which also serves as the shaft for' the'pumping. elements of the reciprocating pump. The shaft 24. and the opposite wall 1 of the housing 2| 'from that to which the rotary pump housing is secured is provided with a suitable shaft bearing 25 that is secured to the pump housing by means of suitable bolts 26. f 1

The top wall'of the housing 2! is provided with an opening 21 for receiving the lowermost end 'of a cylinder"defining block 28 having a peripheral flanged portion 29 for receiving holding down screws'or bolts 30 by'means' of which the block is secured to the housing 2|.

The block 28 defines a pair of alignedoylinders'3l' and 32 for reciprocably and operatively receiving the pistons 33 and 36. -Eachof the pistons is connected by means of a-connecting link 35 to an eccentric on-the shaft 24, the cocentrics for actuatingrthe two pistons being in 180 relation. That is, when one piston is at the bottomof its stroke, the otherpiston will be at the top of its stroke.

It will be noted that-the cylinder bores .extendentirely through the cylinder block and are coveredby a cap member 36 which deflnesrthe outlet manifoldfromthe cylinders, a suitable gasket '31 preferably being provided at the joint between the cap and the uppermost end of the cylinder block.

Asv shown in Figure 3, a common inlet manifold 38 is suitably secured ,at one side of the cap member, this manifoldhaving separate inlet connections 39 and M) respectively communicating through ducts M with the interior of the cylinders, the ducts terminating in the un-.

dersurface' of the cap 36 in each cylinder. The ducts 4| in each cylinder are respectively controlled by a downwardly opening memberor flap This housing terminates at one This plate is valve 42 which is anchored at one end as at 43 to the undersurface of the cap 38 with its free end overlying the entrance openings of the ducts 4! into the cylinder.

5 As shown in Figure 2, the cap 36 has a longitudinally extending bore 44 having one end connected with a pipe connection fitting l5 and its other end connected with a pipe connection fitting 46. Intermediate the ends of the bore 44,

the cap is provided with portions defining a valve socket 41 axially aligned and above each of the cylinders. This socket is closed at its bottom, except for one or more outlet ports 48.

pansion spring 5! which acts to bias a valve disk 52into seated position over the outlet port from the associated cylinder.

In addition to the valving arrangement of ports as described above, the outlet valve for cylinder 32 is additionally provided with a, small by-pass port 53 which enables a small amount of thefluid being pumped in cylinder 32 to be bypassed around its associated outlet valve disk 52.

' The bottom wall of the housing2l of the reciprocating'pump structure is'provided with a removable closure member 54, as shown inFigure 2, this member being secured over an opening 55 in the housing by means of suitable securing sprews or bolts 56. This closure member is constructed of a metal which preferably has a high heat conducting characteristic, such as aluminum. The member 54 is constructed with a relatively thin shelled integrally formed capped portions! which extends upwardly through the opening 55 into the housing 2| and provides a downwardly opening recess 58 adapted to axially receive therein an electric heating unit 59. This heating unit comprises a body portion ofins'ulating material, such as an asbestos composition, which is'providedwith a helically extending groove 60 in which a suitable heating element or resistance wire 6! is disposed. The ends of the heating element are connected to suitable terminal studs 62 and 63 which are mounted in the body of the heating element and have 50 threaded ends projecting from the recess or V68 socket 58 by means of a retaining bolt extending through the bottom of the cupped portion' and a suitable bore in the body portion of the heater body, a nut 65a being threaded onto the bolt 65 to cooperate with the head of the 0 bolt for clamping the body portion of the heater against the bottom of the cupped portion.

With the construction just described, the heater may'be easily removed from its position in the socket 58 simply by removing the nut 65a, whereupon the heater may be taken out as a unit. Such an arrangement is particularly advanta'geous as it enables ready replacement of a heater should it become burned out, or in the event that it is desired to install heaters for operation on different voltages which may be available in difierent installations of the oil burner equipment. As shown in FigureL'theinterior of the housing 2| is maintained open to atmosphere through 75 a suitable breather 66.

. a hollow conductor 86.

The housing 2| of the reciprocating pumping mechanism comprises a reservoir for receiving oil which is supplied from the outlet connection of the rotary pump through a pipe connection 61, as shown in Figure 1, this pipe being provided with a number of turns which encircle the extension l5 of the blower, these turns being in heat receiving relation with the burner nozzle and the fuel which is being atomized and burned. After encircling, the extension IS, the pipe 6! is carried to the inlet of a float valve 68 having an outlet which is connected by a suitable pipe connection 69 to the interior of the housing 2|.

The float valve 68 operates to maintain a predetermined supply of oil within the housing 2|. Normally this oil level is approximately at the shaft 24 so that the operation of the driving eccentrics for the links 35will act to churn and agitate the oil and enable its being more readily heated by the electric heater in the bottom of the pump housing 2| and by the heat generated by friction during operation of the pump parts.

By conducting the oil through pipe 61 through the turns around extension I5, the heating of the oil is augmented. In fact, after ,the burner 1 has started to operate, the electric heater is deenergized and the oil is suihciently heated by its being passed around the extension IS.

The float valve 68 is also vented to atmosphere through a suitable breather Ill.

On the opposite side of the blower casing H! from the extension l5, there is supported a housing H for the local control mechanism, the housing 1| having a removable cover 12. 7

Referring to Figure 4, the local control mecha nism will now be described. Within the housing, there is provided a supporting bracket l3 which is secured to the rear wall of the housing by means of suitable screws M. This bracket has a forwardly projecting L-shaped flange portion leg 16.

Associated with the uppermost leg T5 of the bracket is an elongate arm 17 which is flexibly connected to the leg 16 of the bracket by means of a leaf spring as shown at E8. This spring permits vertical swinging movement of the arm 11, this swinging movement being adjustable between abutment nuts 19 and 80 threaded on a stud bolt 8|, these nuts being adjustably positionable on either side of the arm TI to limit its swinging movement.

The arm 11 is normally biased in a downward direction by a tensioned spring 82 having one end anchored to the leg 15 of the bracket, and

its other end anchored to the arm 71.

The arm 17' is moved upwardly in response to the action of the thermal responsive closed system. This system comprises a bellows 83 which is rigidly'secured' at one end to the leg 15 of the bracket and has its uppermost end provided with a head member 84 which bears against. the underside of the arm 11 adjacent its connection to the leg 1'6 of the bracket. Connecting the interior of the bellows 83 with a bulb 85 is The bulb, bellows, and conductor are filled with a thermal responsive medium, so that as the temperature to which the bulb 85 is subjected is varied, the bellows 83 will be caused to expand or contract depending upon whether the temperature is increased or decreased. Expansion of the bellows moves the arm 11 upwardly against the tension of spring 82, whereas contraction of the bellows defining a long leg 15 and an uppermost shorter tion by the action of the piston associated with moved up and down in response to variations in temperature of the oil within the housing 2|.

The movements of the arm H are utilized for the opening and closing of switches (preferably of the mercury type) as will be explained presently. For this purpose a switch supporting bracket 81 is'pivoted as at 88 for swinging movement, and this bracket is pivptally connected to one end of a link 89, the other end of this link being pivotally connected to the free end of arm 11.

One end of the bracket 8! carries a two-electrode type mercury switch 90 which is adapted in the down position of arm ll to interconnect a pair of circuit "conductors 9i and 92. The other end of the bracket 81 carries a threeelectrode mercury type of switch 93 which is arranged in the closed position of switch 90 to interconnect conductors $4 and 96. However, when the arm TI is raised, the bracket 87 will be rotated clockwise and carry the switches to such position that the switch 90 will open its contact and switch 93 will disconnect the conductors 9t and 96 and connect conductor 9 with a conductor 91. The conductors connected with the switch may be brought out to suitable terminal blocks within the housingv ll.

There is also associated with the control mechanism, just described, an adjustable air intake valve 98 which is also supported upon the leg 15 of bracket 73. This valve is provided with a stem 99 having a threaded extension E00 at its uppermost end for receiving suitable nuts IOI, the threaded extension extending through a suitable opening in the arm ll. By adjusting the nuts It", the amount of opening of the air valve may be determined in relation to the movement of arm 11. Moreover, regulation of the valve opening is attained by means of an adjusting screw 502. The air valve is connected to and controls the inlet of an air pipe E03.

Oil system .Referring now to Figure 7, the oil system will now be described. The oil is taken from a'suitable source of supply such as a tank Hit, which might be placed in any suitable location. Oil is drawn from the supply tank through an oil pipe H15 by the action of the rotary pump I1.

From the outlet of this pump, the oil travels through the pipe 6'! and traverses the coil porwithin the casing 21 at all times.

From the casing 2| the oil is drawn through a metering valve I05 of conventional construccylinder 32 of the reciprocating nism.

After the oil passes through the metering valve, it is carried through a pipe H11 and carburetor I08 to the intake of cylinder 32.

This carburetor is constructed as specifically shown in Figure 6, and comprises an elongate pumping mechabody portion I09 having a longitudinally extending bore IIO enlarged at its ends for receiving pipe connections. At' its lowermost end, the bore I I is tapped by the connection of pipe I03 which extends laterally from the body. .The body I09 is so positioned in relation to the float valve 68 that the oil level in the float valve will also maintain an oil level in the body I09 which is above the entrance of the air pipe I03. It will therefore be evident that as the oil flows through the body I09 from the bottom towards the top there of, as shown in Figure 6, air will be'drawn into the oil stream. 1 The air and oil will thus become mixed and an attenuated mixture of air and oil formed. It will thus be apparent that the piston acting in cylinder 32 will pump an attenuated mixture of air and oil and discharge it into the the reciprocating pumping mechanism is conne'cted to a pipe I25 which conducts the air and oil as they are mixed to the atomizing nozzle outlet manifold of the reciprocating pump mech- 4 anism.

The rotary pump I1 is arranged to pump a greater amount of oil than will be required to be delivered through the metering valve. The surplus oil, particularly when the float valve is closed, will be delivered through a return pipe III back to the supply source in tank I04. The pipe III contains a relief valve II2, which is set to open at approximately one to two pounds oil in its return to the supply tank.

The attenuated mixture of air and oil, the oil having been carbureted in the carburetor I08 and further mixed under pressure in the cylinder 32 and discharged into the outlet manifold of the reciprocating pump mechanism-will build up a pressure in a pipe line '3 which connects, the outlet manifold through a ball relief valve H4 with the pipe III just ahead of relief valve H2. The relief valve H4 is of the ball type and is set to open at substantially 90 pounds pressure.

Connected ahead of the relief valve I is a pipe I I5 whichconnects through a bleeder valve II6 to a closed tank or container I I1.

The construction of this bleeder valve is disclosed in detail in Figure 5. Aswill be noted, the bleeder valve comprises an elongate casing II8 having a longitudinally-extending bore II9 which communicates at its innermost end with an expanded bore portion I to form a valve seat. The valve mechanism is housed within the portion I20 and comprises a valve member i2I having a rounded nose portion adapted to seat upon the innermost end of the bore I I9, the valve member being resiliently actuated to seated position by means of an expansion spring I22.

The rounded seating end of the valve member is provided with a small surface groove I 23 which permits bleeding of air from the pipe II3 into the tank 1. During normal operation of the burner, the bleeding of air into the tank II! will build up an air pressure in the tank to the operating pressure at the nozzle. This tank obviates surges and the air therein is used for purging and cleaning as described hereinafter. During normal operation, the valve member I2I will remain in closed position as shown in Figure 5.

Air system As previouslydescribed, air is taken in through the pipe I03 by the carburetor I08 and mixed with the pumped oil to form an attenuated mixture of air and oil. The piston of the recipro- I6, where the mixture is discharged at pressures ranging from substantially to 150 pounds. The atomized fuel, when ignited, is burned in the combustion supporting air delivered from the blower through the tubular extension I5.

A governing effect is provided by mid-point positioning of the valve 98 which is determined by the temperature of the compressor as this temperature determines the condition within the bulb 85. Thus where there is a high boiler room temperature the compressor chamber tem perature will be higher, causing the bellows 83 to expand and push its head member 84 against l the bar 11, thus opening the valve to admit adpressure acting in the direction of flow of oil ditional air and maintain the desired even flame.

Control mechanism In addition-to. the control previously described as being contained in the housing II, additional control devices are utilized in order that the burner may be automatically started and stopped according to the heating requirements.

As further shown in Figure 7, the control mechanism in the casing 1| may be coordinated with additional control relays, etc., which may be variously constructed to accomplish the desired control of the burner. have shown schematically a repulsion type relay as generally indicated at I25. This relay comprises a magnetic yoke I21 with which there is associated a fixedly mounted primary Coil I28 and a movably mounted secondary coil I29 which perature of the bi-metallic metal of the latch eating pump mechanism which is associated v with cylinder 3I is utilized for the pumping of air only, the inlet to this cylinder being supplied is supported on a pivotally mounted arm I30. With this type of relay, when the primary coil I28 is energized, the secondary coil is energized due to the transformer effect between the coils. At the same time, magnetic repulsion between the primary and secondary coils causes the secondary coil to swing away from the primary coil.

This action brings the arm I30 to a position in which it will close a pair of contacts I3l. The connection to this relay will later be described.

Another device which is desirable in oil burner control isa safety switch such as diagrammaticall shown at I32. This switch may constitute a two-electrode mercury switch I33 carried on a swingable bracket and normally biased to open position. The bracket is arranged to be latched by a suitable latch member I34 of bi-metallic material. The safety switch is moved to normally closed position in which it is latched by the bi-metallic member I34, but upon the temreaching a predetermined .amount, the latch member will release the safety switch and permil; it to be biasedto open position. The temperature of the bi-metallic latch member is controlled by means of a heating coil I35.

Also included in the control diagrammatically represented herein is a flue thermostat relay I36 which is responsive to flue temperatures, when cold, to interconnect a pair of contacts I31, but,

In the present instance, I-

I31 and close when heated, to open the contacts anotherpair of contacts I38.

As in most control systems for oil burners, the present system includes a room thermostat as generally indicated at I39 having a pair of normally opened contacts I40, which are adapted to close upon a rise of room temperature.

Operation Let it be assumed that the oil burner has been standing idle and that the oil in the casing 2| is cold; The control devices will then be in their normal positions as shown in Figure 7.:

Under such conditions, it will be noted that the primary coil of the repulsion rela will be connected to a source of current supply I 4| through the following circuit: from the side of the current supply through the closed contacts of safety switch I32, conductor I42 to one side of primary coil I28, conductor I43, and thence through conductor I44 to the other side of the main current supply. Thus the primary coil is across the line and will be energized. However, the primary coil will not repulse the secondary coil I29, since it is open-circuited as the result of the contacts I40 of the room thermostat in the secondary coilcircuit being in open posithence back to the other terminal of coil I29.-

The secondary coil circuit thus being completed, current will flow in the secondary coil with the result that the secondary coil will be repulsed from the primary coil, and the relay will operate to close contacts I3 I.

Closing of contacts I 3I energizes the heater 59 in the bottom of easing 2I through the following circuit: from one side of the current sup ply I4 I, through the contacts of the safety switch I 32, conductor I42, contacts I3I, conductor I50 to one side of the heating element of the heater 59, and the other sid of this heating element through conductor 96, the closed contact switch 93, and thence through conductor 94 to the other side of the current supply.

The heater 59 continues to pro-heat the oil in the casing 2I. This heating of the oil continues until it reaches substantially a temperature of 105 F. As the temperature of the oil continues to increase, the closed thermal responsive system expands the bellows 83 and causes switches 90 and 93 to move to a position wherein they tilt downwardly to the right instead of downwardly to the left. In this changed position, the contacts of switch 90 are opened, and conductor 94 is disconnected relative to conductor 96, whereupon the circuit through the heater 59 is opened. At the same time, conductor 94 is connected with conductor 91 and the motor C of the oil burner becomes energized through the following circuit: from one side of the electric supply circuit, through the contacts of safety switch I32, conductor I42, contacts I3I, thence through conductor I 5| to one terminal of the motor, from the other terminal of the motor through conductor 91, the right hand contact of switch 93, andthence through conductor 94 7 back to the other side of the main current supply.

The motor now being energized starts 'to operate the blower and pumping mechanisms. The action of cylinder 32 draws heated oil through the metering valve, and the carburetor I08 where air is combined with the oil as previously described, it being understood that the valve 98- is so regulated that when theswitches and 93 are actuated as just described, the valve 98 will also be opened to admit air to the carburetor.

At the same time, cylinder 3I starts drawing in air which is compressed and combined with the attenuated mixture discharged from cylinder 32. The mixed oil and air isthen conducted throughpip I25 to the nozzle I6, where it is atomized into a combustion supporting atmosphere produced by the air issuing from the blower A through the extension I5.

Simultaneously with the starting of the motor, energization of the motor completes a circuit through the primary .of an ignition transformer as follows: from one side of the main current supply I4I, through the contacts of the safety switch, conductor I42, contacts I3I, conductor I5I, conductor I53, contacts, I31, conductor I54 to one terminalof the primary of the ignition transformer, from the other primary terminal through conductor I55, and thence through con,- ductor I44 back to the other side 'ofthe supply circuit. The ignition transformer thus being energized, an ignition spark is emitted adjacent the nozzle I6 between a pair of electrodes I56 which are respectively connected by conductors I51 and I58 to the respective ends of the secondary. winding of the ignition transformer;

Assuming now that the atomized fuel issuing from the nozzle I6 is ignited, the hot gases passing out the flue of the furnace will actuate the flue thermostat to such position that it will open its contacts I31 and disconnect the ignition transformer. At the same time it will close its contacts I38 which operate to short circuit the heater I35 of the safety switch through the following circuit: from one terminal of the heater, through conductor I46, conductor I59, contacts I38, conductor I60, and thence through conduc- 1815 I41 tothe Other termina1 of the heater coil The burner will now continue to operate until sufficient heat is furnished to the room containing the room thermostat. When the temperature has reached the amount for which the room thermostat is set, it will open its contacts I40 and thereupon open-circuit the secondary coil I29 of the repulsion relay. The secondary coil then moves towards the primary coil and opens the contacts I 3|, whereupon the motor circuit is deenergized and the burner discontinues its operation.

In the event that the ignition spark does not ignite the atomized fuel issuing from'the nozzle I6, then the flue thermostat continues to retain contacts I31 closed. Since the contacts of switch 90 are at this time opened, the heating coil I35 will be in the room thermostat circuit of the secondary coil I29. The heating coil I 35 is thus energized from the secondary coil I29, and due to its heating effect upon the thermostatic strip of bi-metal I34, this latch will be deflected after a predetermined interval of time to a position wherein it will release the safety switch I32. so I that the mercury switch I33 will be moved under j its biasing spring to a position the action of wherein it will open its contacts and shut down 6 the motor driving the burner. The burner will then be cut out until such time as the safety switch is manuallyreset.

When the burner shuts down, the-air which has become stored in the tank 1 will open the bleeder-valve H6 and be. discharged through the pipe I25 and nozzle l6, thus purging and cleaning out the system." i j y 7 a If; for any reason during the operation of the oil burner, the nozzle 16 should become clogged so as ;to prevent the atomization of'the attenuated fluid thereby, a pressure will build up be- -.hind the nozzle. 'In my improved system, this I pressure is relieved by the opening of 'reliefvalve' I [4 which permits the passage of fluid from the 1 outlet manifold of thereciprocating pump mechanism through the by-pass valve H2 back to .the supply tank. a

If the burner has been operating continuously or at sufficiently close intervals to have kept the oilin the casing 2| of the reciprocating pumping mechanism at a sufliciently high temperature,

the burner will start up immediately upon a call for heat by the room thermostat and there will not be instituted the time delay previously de-- scribed for energizing the heater 59 for preheatform a combustible mixture, before the mixture is atomized in theburner nozzle, the amount of air I claim as my invention: 1. In an oil burner having a nozzle, a conduit to said'nozzle,'means for mixing air and oil and delivering the mixture under pressure through said conduit, driving means for said first means, and a thermally actuated mechanism responsive 1 said tank, said last named conduit connecting with said first named conduit, and valve means for releasing said compressed air fromsaid tank when said driving means is out of' operation to fiush said first conduit and said nozzle.

' 2. In' an oil burning apparatus in which mixed 7 air and oil are supplied througha conduit to a fuel nozzle, means for pumping air, means for storing said pumped air during operation of the beingautomatically controlled; which embodies 7 improved means for carbureting the oil by the injection of air before the oil reaches the burner nozzle; which includes novel pumping mechanism in which the oilmay be pre-heated and mixed with air under pressure; which is provided with improved means for purging and flushing the oil n'ozz1e', when'the burner isshut down; which'has an improved relief arrangement in the oil path, whereby oil maybe returned to a source of supply whenever the burner nozzle becomes clogged;

afbur'ner arranged to utilize metered quantities of oil and by-pass surplus pumped 011 back to a supply source; and which utilize improvedcontrol means for delaying starting of the burner, when cold, until the oil has been pre-heated to a predetermined temperature. Now, it is, of course, to be understood tha although I have described in detail the preferred embodiment of my invention, the invention is not to be thus limited, but onlyv insofar as .defined bythe scope and spirit of the appended claims.

burner, a conduit for connecting the means for storing air and said first named conduit and a valve for releasing said stored air through said last namedfconduit when the burner is shut down to flush said first named conduit and said fuel nozzle, said valve including means defining a small inlet opening for flow of air into said storage means during operation of said burner, and being'const'ructed and. arranged to shift in response to pressure in said storage means to define a. large outlet opening for now offair out of said storage means when said burner is shut down.

3. In an oil'burning apparatus in which mixed air and oil are supplied-through a conduit to a fuel. nozzle, means for pumping air, means for storing" said pumpedair during operation of the burner, a conduit-for connecting said storage and pumping means, said last named conduitconnecting with'said first named conduit and a valve for releasing said stored air when the burner is shut down toflush said first conduit and said fuel nozzle, said valve including a tubular casing hava ing different sized bores therethrough defining invalve member having a small surface groove permitting bleeding of air from said air pumping means into said storage means during operation of said air pumping means, said valve member being moved away from said seat when said air pumping means is out of operation to permit air to. flow through said bores to flush said first named conduit and said fuel nozzle.

CHARLES L. RAYFIELD. 

